DC Machine

Advantages:The series motor has the highest starting torque for a given power rating. When the motor is overloaded, the speed drops and the torque increases. While delivering high torque during an overload, the series motor draws less current and power from the source compared to a shunt or compound DC ...Read More

DC Machines can be tested by three different methods namely Direct Method, Indirect Method and Regenerative Method. Direct Method of testing of DC Machine, also known as Brake Test (if carried out for a DC Motor) will be discussed in this post. Direct method is suitable for small DC machines ...Read More

D. C Motor Starting:Why Starter Needed:Let Vt = Terminal VoltageIa = Armature Currentra = Armature ResistanceEa = Back emf = KaØWmAt the time of starting, speed of motor is zero hence Wm = 0, therefore there will not be any Back / Counter emf. Hence if we look into the ...Read More

Long Shunt and Short Shunt DC Compound Machine:In short shunt DC Compound Machine, shunt filed winding is connected across the Armature whereas in Long shunt connection it is connected across the line terminal. But there is no difference in operating characteristic in two types of machine.Characteristics of DC Shunt Generator:There ...Read More

As discussed in earlier post, Purpose of Interpole in DC Machine, there are two types of effect of armature reaction on the main field flux: 1) Distortion in Main Field Flux 2) Net reduction of Main Field Flux Due to the above two effects of armature mmf, there ...Read More

There are two types of winding in a Conventional DC Motor, namely Filed Winding and Armature Winding. The purpose of Field Winding is to produce the working magnetic flux in the air gap and wound on the stator of the motor whereas armature winding is wound on the rotor. But ...Read More

For understanding the role of Interpoles, we need to understand the effect of armature reaction in the DC Machine. The effect of armature mmf on the main field flux is to distort the main field flux and to reduce the net main field flux. The figure below, shows the effect ...Read More

In the last post "Need for Electrical Braking in Electrical Drives", we discussed the various reasons which call for Electric Braking. Brakes are used to reduce or cease the speed of motors. Braking of Motor can be classified into three types:Regenerative Braking.Plugging type Braking.Dynamic Braking.In this post we will focus ...Read More

DC Motor speed control means to have full control on the speed of DC Motor. The variation in speed of DC Motor because of variation in load is not the speed control. Therefore intentional variation in speed of DC Motor is called Speed Control.As we know that for a DC ...Read More

In previous post “SpeedControl of DC Motor” we discussed the method of speed control of DC Motor by ArmatureCircuit Resistance Control Method. In this post we will discuss the method of speed control of DC Motor by varying the Field Flux which is known as Field Weakening Method. By Field ...Read More